As the resolution of computer displays such as LCDs has become higher, display quality has improved. As a result, a user is able to recognize more information content at a glance because of the increased amount of information displayed. Nevertheless, a problem of lowered visibility has arisen because the size of icons and characters has been reduced. This problem could be resolved by temporarily changing the display resolution. However, it is preferable to display various kinds of information simultaneously using multiple resolutions on the same display.
An example of simultaneous display with multiple resolutions is disclosed in U.S. patent application Ser. No. 10/427,386 filed on Apr. 30, 2003, and assigned to the present assignee. In this example, a high resolution three-dimensional graphics window and a low resolution two-dimensional graphics window can be displayed simultaneously on a single high resolution display by employing a frame buffer including a first mode area for high resolution and a second mode area for low resolution. The contents of the first mode area of the frame buffer are directly displayed on the display screen, while the contents of the second mode area are displayed after expanding the width and the height each by a factor of two. Accordingly, it is possible to display the contents of the second mode area, for example a low resolution two-dimensional graphics window including icons and characters, on the display screen without lowering its visibility while displaying the contents of the first mode area, for example a high resolution three-dimensional graphics window, on the same display screen.
More specifically, in the case of single-resolution display, when high resolution display is performed using, for example, a CAD application, a design drawing of an automobile might be displayed in detail, whereas the visibility of icons and characters in a tool bar might be greatly reduced. If the multiple resolution display method described above were applied to this case, a tool bar could be displayed with larger size thereby to improve its visibility while a high resolution design drawing is displayed.
The multiple resolution simultaneous display function described above can be provided in the form of, for example, a display driver. An example of the conventional drawing methods using such a display driver is shown in FIG. 1.
Referring to FIG. 1, first an application program 30 determines whether a target to be drawn is a high resolution window. If the target is a high resolution window, a high resolution drawing command (glDrawPixels of OpenGL, for example) is sent to a display driver 32. If the target is not a high resolution window, then a low resolution drawing command (BitBlt of Microsoft® Windows®, for example) is sent to the display driver 32. When the display driver 32 receives the high resolution drawing command, it executes a drawing operation as specified by the command, and writes its results into a frame buffer (VRAM) 34. On the other hand, when the display driver 32 receives the low resolution drawing command, it enlarges an object to be drawn by doubling its width and height, and writes the results into the frame buffer 34. Finally, when the contents of the frame buffer 34 are read out to a display 36, the first window having a high resolution and the second window having a low resolution are displayed simultaneously on the same display 36 without reducing the visibility of icons and characters of the second window.
In conventional drawing methods such as the one described above, however, the distinction between the high and low resolution drawings is made based on the difference between two drawing commands (API), for example, OpenGL and Windows GDI. Therefore, application developers have to be familiar with both commands.